An advantage of terrain occurs when military personnel gain an advantage over an enemy utilizing, or simply in spite of, the terrain around them. The term does not exclusively apply to battles, and can be used more generally regarding entire campaigns or theaters of war.

Mountains, for example, can block off certain areas, making it unnecessary to station troops within the inaccessible area. This deployment strategy can be applied with other formidable environmental features as well, such as forests and cliffs. In the former instance, dense vegetation can provide concealment for tactical movements such as setting up an ambush. In the latter, the elevation can provide an advantage to soldiers using projectile weapons, such as arrows or artillery pieces. Elevation itself is perhaps the most well-known example of terrain advantage, with gravity working to the advantage of the more elevated party.

Many ancient fortifications made use of terrain, such as this Suramifortress.

The Battle of Agincourt- The nearby trees created a choke point where the French were hit by English long bowmen. The main environmental factor in English victory was the extremely muddy area. The field had recently been plowed, and it had been raining recently.[1]

The battles of Morgarten (Swiss confederation, 1315), Lake Trasimene (Roman empire, 217 BC) and the Battle of Teutoburg Forest (Roman empire, 7 CE) signified battles where the attacker was forced to fight at a narrow place between a lake (or a swamp) and hills.